Well, some might be really amazed. They could see a new side of Deku that they never knew before. His singing might show a different level of confidence or a hidden talent, so they would probably cheer him on.
He might cry a lot. Deku is very emotional, and being cheated on would be a very painful experience for him. He could also get angry, which is rare for him, but this situation would be so unjust that he might not be able to hold it in. He'd probably start to question his self - worth too, thinking that there was something wrong with him that made his partner cheat.
Deku might be initially shocked. He's used to Bakugou's aggression, but an actual injury is different. He could be in pain and disbelief at first. Then, he might try to downplay it, especially if he doesn't want to cause trouble for Bakugou, because Deku is generally a very forgiving character.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). It has a large collection of My Hero Academia fanfictions, and you're likely to find some great 'class 1a meets manga deku' ones there.
There's also 'When Class 1a Meets Manga Deku'. This fanfiction focuses on how the students of class 1a react to a Deku who has all the powers and abilities as depicted in the manga. It shows their initial shock, followed by their attempts to work together with this new version of Deku. The story also delves into the relationships between the classmates as they face various challenges.
Midoriya's friends like Uraraka and Iida would be extremely worried. They would immediately start looking for him. Uraraka might use her quirk to search in the air, while Iida would lead the ground search with his speed. Bakugo, on the other hand, would be furious. He would probably go on a solo mission to find Deku and take on Todoroki without hesitation.
His friends would be really shocked at first. Uraraka might be the first to try and comfort him, seeing as she has a kind heart. Bakugo, on the other hand, would probably be both confused and a bit angry at the situation. All - Might would likely feel a sense of responsibility to protect Deku even more than before. The teachers at UA would probably start researching how to reverse the transformation immediately.
His classmates would probably be very concerned. Some might immediately run to get the teacher or the school nurse. Others might gather around Peter, asking if he was okay and trying to comfort him.
He might be initially shocked. Snape is used to students being intimidated by him, so Hermione's outburst could catch him off - guard. He may glare at her silently for a moment, trying to regain his composure.